This application is a continuation of International Patent Application No. PCT/EP03/06307 filed on Jun. 14, 2003, designating the United States of American, the entire disclosure of which is incorporated herein by reference. Priority is claimed based on Federal Republic of Germany Patent Application No. DE 102 37 664.6 filed Aug. 16, 2002.
The invention relates to a cylinder head for a water-cooled multi-cylinder internal-combustion engine having two intake valves and outlet valves per cylinder, a cylinder head cooling chamber with inflow and outflow openings for the coolant, and a receiving opening for a spark plug, which receiving opening is arranged centrally relative to the cylinder head cooling chamber of a cylinder.
In German Patent Document DE 100 21 525 A (corresponding U.S. published application US 2002-162520), the cooling circuit for a multi-cylinder internal-combustion engine is illustrated and described, in the case of which, for a coolant flow distribution which meets the demands, approximately ⅔ of the coolant flow caused to circulate for cooling the engine are guided through the cylinder head housing. So that all cylinder head units are uniformly cooled, it is also provided that, relative to the longitudinal axis of the cylinder bank, coolant flows transversely through the cylinder head housing. These are measures for permitting the removal of the high radiant heat generated during the combustion from the cylinder head housing. From German Patent Document DE 199 43 001 C1 (corresponding U.S. Pat. No. 6,499,444), it is also known to cool a hot point in the cylinder head by an additional duct which is aimed at the hot point and carries cooling water. Furthermore, it is known from German Patent Document DE 35 16 453 C2 (corresponding U.S. Pat. No. 4,699,092) to steer the cooling liquid flow by means of ribs arranged in the cylinder head in the direction of a spark plug dome.
It is an object of the invention to provide further measures in order to effectively and uniformly cool the high-temperature-stressed areas of the cylinder head in a targeted manner.
According to the invention, this object is achieved by providing a cylinder head for a water-cooled multi-cylinder internal-combustion engine having two intake valves and outlet valves per cylinder, a cylinder head cooling chamber with inflow and outflow openings for the coolant, and a receiving opening for a spark plug, which receiving opening is arranged centrally relative to the cylinder head cooling chamber of a cylinder, wherein on an inflow side in the cylinder head cooling chamber, a main cooling flow runs between the two outlet valves in the direction of the receiving opening for the spark plug, while two secondary cooling flows are provided at two edge areas of the inflow side.
As a result of the characteristics of the invention as described in the preceding paragraph, a cooling adapted to the temperature load in the cylinder head is achieved inside the cylinder head of a multi-cylinder internal-combustion engine, during which cooling, a main coolant flow is guided between the two outlet valves of the four-valve engine in the direction of the spark plug dome, while the edge zones of the cylinder head cooling chambers are supplied with secondary cooling flows.
Additional advantageous embodiments and improvements of the cylinder head according to preferred embodiments of the invention for a water-cooled multi-cylinder internal-combustion engine are described below and in the claims.
According to certain preferred embodiments of the invention, as a result of the guiding ribs provided at the level of the receiving opening for the spark plug, the coolant is advantageously guided into the area of the high-temperature-stressed spark plug dome. As a result of the fact that the cross-sections of the two guiding ribs have different constructions, a transverse flow is generated behind the guiding ribs which counteracts the formation of so-called dead water regions and contributes to the fact that a sufficient coolant supply exists also in the area of the intake valves.
According to certain preferred embodiments of the invention, as a second measure for generating a transverse flow in the rearward area of the intake valves—viewed in the flow direction of the coolant—, it is suggested that diameters of the outflow openings have different sizes.
According to certain preferred embodiments of the invention, for aiding the cooling of the hot point existing in the spark plug dome area, a cooling duct is additionally provided on the inflow side in the cylinder head, which cooling duct guides coolant directly to the hot point.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.